In short accelerated development is complicated and should be looked at on a case by case basis, everything else seems to be usable universally.
Nobody has yet disagreed with the universal skill scaling, so i guess we can go from here to the skill tiers, and what sort of abilities they will get. What i can think of off the top of my head which could be wrong:
Al- Is on the lowest level with second rate skills, but even he has instinctive action.
Emilia? Who has that analytical prediction feat, and would also get instinctive action scaling to Al. Julius can also fit here.
Crusch and Priscilla- Would also get analytical prediction and instinctive action.
Elsa- Has info analysis for that Puck danmaku feat, and analytical prediction. Arc 4 Garfiel is around here, with analytical prediction resistance, and attack reflection.
Arc 5 Garfiel- Nothing exactly new from what i can remember.
Ex Novel cast? They don't exactly show anything new either from my memory, just more info analysis and analytical prediction. But if we say for example even Emilia has analytical prediction, and the Ex cast skills are perfect, maybe we can say their one would be better.
Old Wilhelm- Theresia's crazy precision feat of disabling limbs. I assume Wilhelm dealing with a large number of Petelguese's attacks with dirt, would be info analysis, while predicting them is analytical prediction. Kind of more of the same, though Wilhelm's analytical prediction is probably better than the others since he can predict invisible stuff.
Ram, and Ley/Gluttony- Not quite sure, we have seen Roy, beat both Julius and Ricado, and they are said to have techniques which have a lifetime of experience, and also that even a lifetime of training can't reach. Wilhelm and Zombie Theresia, are said to beyond the realm of humans, so it would be equating being beyond humans, to Gluttony's being beyond lifetime of training, i guess it fits, which is what we currently accept. Ram's skill was complimented by Wilhelm, was shown to be fairly skilled against Ley, albeit she was probably physically superior. Anyway assuming they all are around the same level, they get damage reduction and power mimicry.
I don't think Young Wilhelm adds anything new.
Peak Wilhelm, Thersia, Kurgan- Probably better info analysis, and analytical prediction, with ways to counter them. Plus resistance to extrasensory perception scaling to Cecilus.
The tiers above don't really add much, unless i am forgetting something, so won't get into them.